Drifting of the null or zero point in various types of transducing or measuring devices used in such applications as weighing scales and signature verification systems is well-known. Such a null or zero reference drift is intolerable in the case of remote unattended installations of such devices and systems as mentioned above, since frequent manual adjustments cannot be made in such remote installations. Various automatic means for compensating such offset errors have been developed, and function, in general, by virture of careful attention to design, utilization of high-grade low-drift components, and suitable inclusion of compensation components exhibiting complementary drift characteristics. Such means generally function entirely within the analog signal domain, are costly and achieve varying degrees of success due to component tolerances.
In the case of hybrid computational systems, such as signature verification systems, which embrace both analog and digital signal domains, utilization of available digital components in large part already present in the system offers the opportunity for the provision of accurate, efficient and inexpensive drift compensation means.